The electrochemical behavior and characterization of the anodic oxide film formed on titanium in NaOH solutions |
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Authors: | Magdy A Ibrahim Dujreutai Pongkao Masahiro Yoshimura |
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Institution: | (1) Center for Materials Design, Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan, |
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Abstract: | Titanium dissolution and passivation were studied in NaOH aqueous solution using open-circuit potential, potentiodynamic
and potentiostatic techniques. Potentiodynamic data showed that the active-passive transition involves active metal dissolution
followed by formation of a poorly conducting passive oxide film that passivates the electrode. The critical current density
varied with pH as d log<I> j</I><SUB>m</SUB>/d pH=-0.098 in the pH range 11.00–14.00, while the passivation potential is changed
according to the following two features: at pH 10.55–13.00, d<I>E</I><SUB>m</SUB>/d pH=-0.06 V; and at pH 13.50–14.00, d<I>E</I><SUB>m</SUB>/d pH=-0.40 V.
The apparent activation energy, E*, was calculated from the slope of the Arrhenius plot and was found to be 12.6 kJ mol–1. Current-time transients showed that the growth of titanium oxide passive film is a diffusion-controlled process. XPS measurements
indicated that the passive oxide film consists mainly of TiO2 and a mixture of suboxides of Ti2O3 and TiO.
Electronic Publication |
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Keywords: | Titanium electrode Passive film Potentiodynamic data Open-circuit potential X-ray photoelectron spectroscopy |
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